Efforts at progress in the field of pigment gallstone disease have been hampered by controversy on basics such as classification, epidemiology and composition. Difficulty in communication between investigators who are scattered in Japan, the United States and Europe has been a further deterrent. These difficulties can be largely surmounted at this time by holding a workshop to assess the present state of knowledge. In addition, the workshop will 1) examine the role of bile and stone composition as they relate to stone formation, 2) examine the role of infection, stasis, hemolysis, calcium binding by proteins and physicochemical factors in stone pathogenesis, 3) identify animal models, and 4) review present knowledge concerning pigment stone dissolution and treatment. A multidisciplinary group of investigators will present papers, provide criticism and generate new ideas. The conference is tentatively planned for May, 1981, and will be held in Philadelphia, PA.